1. Field of the Invention
The present invention relates to a novel apparatus used in a dual extrusion process for the preparation of soap which apparatus permits the production of soap bars having comparable aesthetic quality on both the inner and outer face of the soap log. In particular, the invention relates to the use of a novel eyeplate in the dual extrusion process providing the above-described benefits. The invention further relates to a novel process for producing soap bars in a dual extrusion process wherein both faces of the bar have comparable aesthetic quality and which process comprises the use of the novel eyeplate.
In a preferred embodiment of the invention, the novel eyeplate is used in combination with upper and lower eyeplate baffles in the nosecone of a plodder.
2. Background
Striated soap has apparently become very popular with the consumer due to the aesthetics of the soap.
Due to limitations imposed by the Federal Drug Administration (FDA) in 1976 on the type of coloring system which can be used in the preparation of soap, it has proved very difficult to obtain desired striation aesthetics. Specifically, using the colors which are required under FDA regulations, the color mix has a tendency with time to blend throughout the bar (thereby reducing the contrast between the striation and the rest of the soap) and thus reduce the aesthetic quality of the soap. In addition, it has been found that striated soap smears when passed through an orifice plate of an extruder.
Striated or variegated soap may be produced in various ways. Colored liquid may be mixed with soap filaments in a worm plodder prior to extrusion of the billet as is taught in U.S. Pat. No. 3,485,905 to Compa et al. It has also been disclosed to make variegated soap by introducing colored liquid through the worm of a plodder as described in U.S. Pat. No. 3,676,538. It has further been proposed to make variegated soap by bringing together differently colored soaps from separate plodders or the like in a mixing device which extrudes the mixture as a continuous billet. In all of these devices, a soap billet of generally rectangular cross-section is extruded from the cone of the final plodder.
It has been observed that the color at the surface of the billets of most variegated soaps extruded from plodders is usually diffused and the striations indistinct at the surface. This problem has become even more acute since the FDA restrictions discussed above on the type of coloring systems which can be used during preparation of the soap.
In order to highlight the striations, a number of solutions have been suggested by the art.
U.S. Pat. No. 3,485,905 to Compa describes a process in which filaments of soap are compacted and forced by a rotating worm in a cylinder through a nozzle which preferably has attached cutting edges to shave-off 1/32 to 1/16 of an inch of the surface as the bar is extruded through the nozzle. There is no discussion of the flow pattern of soap through the plodder or nosecone and no mention of an eyeplate with a relief system for controlling the flow of soap or the effect on the aesthetics of the soap bar the flow pattern may have.
U.S. Pat. No. 3,857,662 to Ratz teaches a process and apparatus for producing striated soap in which soap is extruded as side by side billets through a die having closely spaced openings corresponding to the billet cross sections. The die further has slots adjacent to the outer sides of the openings for shaving away outer surface layers. In this patent, a narrow land 18 is used to separate the billets. This narrow land has no opening or port through which soap can flow to provide relief in the flow pattern when the billets are extruded through openings in the middle. There is no discussion or appreciation of what effect a relief in the flow pattern may have on the aesthetics of the log, particularly on the inner faces of the logs.
U.S. Pat. No. 3,784,533 to Mach teaches a method and apparatus in which soap is first extruded through a nozzle having an opening and then glossed as it passes through the opening in order to impart gloss. Again, there is no orifice or port in the middle where the soap is extruded into two or more bars and no recognition of how such an orifice might affect flow patterns and the aesthetics of the inner log face.
U.S. Pat. No. 3,868,208 to Fischer teaches a nozzle plate assembly for obtaining an improved surface finish on high speed extrusions without requiring trimming.
In none of these references is there provided an apparatus or method for overcoming the problem of two perceptibly different surface patterns between inner and outer log faces which is a well known phenomenon that is typically associated with striated soap produced in conventional dual extrusion processes.
Thus, it would be greatly desirable to find an apparatus or method which could overcome the problem of different surface patterns produced in dual extrusion processes and which could produce bars with clearly defined and comparable surface patterns on both the inner and outer log surfaces.